Solving SCSI problemsNote: This information also applies to Serial Attached SCSI (SAS) problems.For any SCSI error message, one or more of the following devices might becausing the problem:v A failing SCSI device (adapter, drive, or controller)v An incorrect SCSI termination jumper settingv Duplicate SCSI IDs in the same SCSI chainv A missing or incorrectly installed SCSI terminatorv A defective SCSI terminatorv An incorrectly installed cablev A defective cableFor any SCSI error message, follow these suggested action in the order in whichthey are listed until the problem is solved.v Make sure that SCSI devices are turned on before you turn on the server.v Make sure that the cables for al external SCSI devices are connected correctly.v If an external SCSI device is attached, make sure that the external SCSItermination is set to automaticv Make sure that the last device in each SCSI chain is terminated correctly.v Make sure that the SCSI devices are configured correctly.Solving power problemsPower problems can be difficult to solve. For example, a short circuit can existanywhere on any of the power distribution buses. Usually, a short circuit will causethe power subsystem to shut down because of an overcurrent condition. Todiagnose a power problem, use the following general procedure:1. Turn off the server and disconnect all ac power cords.2. Check for loose cables in the power subsystem. Also check for short circuits, forexample, if a loose screw is causing a short circuit on a circuit board.3. If a power-channel error LED on the system board is lit, perform the followingsteps; otherwise, go to step 4. See “System-board LEDs” on page 15 for thelocation of the power-channel error LEDs. Table 6 identifies the componentsassociated with each power channel, and the order in which to troubleshoot thecomponents.a. Disconnect the cables and power cords to all internal and external devices.Leave the power-supply cords connected.b. Remove each component that is associated with the LED, one at time, inthe sequence indicated in Table 6, restarting the server each time, until thecause of the overcurrent condition is identified.Table 6. Components associated with power-channel error LEDsPower-channelerror LED ComponentsA Fan 4, fan 6, fan 8, fan 9, microprocessor 1, system board (integratedvoltage regulator)B Fan 1, fan 2, fan 3, fan 5, VRM, IDE CD/DVD cable, IDE CD/DVDmedia backplane, microprocessor 2, system boardChapter 5. Diagnostics 175
